e.g. truncate table cascade

Preparation of Test Data
test=# 
create table employees (id integer, name varchar, department_id integer);

test=# 
create table departments (id int, department_name varchar);

test=# 
ALTER TABLE DEPARTMENTS
ADD CONSTRAINT DEPT_PK 
PRIMARY KEY (ID);

test=# 
ALTER TABLE EMPLOYEES
ADD CONSTRAINT EMP_DEPT_FK 
FOREIGN KEY (DEPARTMENT_ID)
REFERENCES DEPARTMENTS(ID);

test=# 
insert into departments
values (1,'IT');

test=# 
insert into departments
values (2,'Sales');

test=# 
insert into departments
values (3,'Marketing');

test=# 
insert into employees
values (1,'John',1);

test=# 
insert into employees
values (2,'Alex',1);

test=# 
insert into employees
values (3,'Guru',2);

test=# 
insert into employees
values (4,'Maximus',3);

test=# 
commit;

Data Check
-- select all rows of parent table 
test=# 
select * from departments;

-- select all rows of child table
test=# 
select * from employees;

Action
-- by using truncate table cascade, parent table and child table data will be removed. 
test=# 
truncate table departments cascade;

Last Data Check
-- select all rows of parent table 
test=# 
select * from departments;

-- select all rows of child table
test=# 
select * from employees;

Info: In Oracle 12c, you are able to use "cascade" clause with "truncate table" statement as well.